Neural refractory properties and behavioural measures of temporal resolution and speech perception in cochlear implant users.

Abstract

Temporal processing is of increased importance in cochlear implant users due to the degraded spectral information provided by cochlear implant devices in comparison to what is heard by normal hearing individuals. Studies have shown that speech perception through a cochlear implant is limited when the transmission of temporal information is impeded and there is considerable individual variability in performance. The health of the underlying neural population is thought to be a key predictor of temporal processing efficiency and speech perception outcomes. The central aim of the work reported here was to attempt to delineate the relative contribution of peripheral and central temporal processing on speech perception. This was achieved by comparing objectively measured temporal properties of the auditory nerve with behavioral measures of temporal processing, and analysis was completed to determine if these measures predicted speech perception in cochlear implant users. An experiment was conducted with 18 unilaterally implanted adults who were stratified by deafness onset, which was used an indicator for neural survival and by stimulation rate. The electrically evoked compound action potential (eCAP) recovery function was used as an objective measure of recovery from refractoriness and the Random Gap Detection Test (RGDT) was used as a behavioral measure of temporal processing. Arthur Boothroyd (AB) word phoneme scores were measured for each subject across a range of presentation levels. The results of this study showed the eCAP recovery function was not affected by deafness onset and stimulation rate and was not a predictor speech performance; but RGDT thresholds were strongly correlated with deafness onset and stimulation rate, and were a very strong predictor of speech performance in the same individuals across presentation level.

More information

Identifiers

Catalogue record

Export record